The present invention relates to a wireless communication device, such as a transponder, that has a plurality of antennas for multi-frequency usage. The wireless communication device comprises a control system, communication electronics, memory, and the aforementioned antennas. A wireless communication device having a pole antenna may be used with one or more loop conductor antennas to achieve the desired operating frequencies. A wireless communication device having a dipole antenna may be coupled across a loop conductor antenna to provide different loop conductor configurations depending on the frequency.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A wireless communication device, comprising: communication electronics connected to a pole antenna having at least one tab; a first loop antenna positioned proximate to the pole antenna and capacitively coupled to the pole antenna at a first frequency, wherein the capacitive coupling forms a first resonant circuit between the communication electronics and the first loop antenna configured to operate at the first frequency; and a second loop antenna positioned proximate to the pole antenna and capacitively coupled to the pole antenna at a second frequency, wherein the capacitive coupling forms a second resonant circuit between the communication electronics and the second loop antenna configured to operate at the second frequency; wherein the communication electronics and the pole antenna form a third resonant circuit configured to operate at a third frequency that is different from the first and second frequencies.
2. The wireless communication device of claim 1 , wherein the pole antenna is positioned between the first loop antenna and the second loop antenna, and wherein the first and second frequencies of the first and second resonant circuits are tuned according to the relative placement of the pole antenna between the first and second loop antennas.
3. The wireless communication device of claim 1 , wherein the first loop antenna and the second loop antenna are formed of a microstrip.
4. The wireless communication device of claim 1 , wherein the pole antenna is a dipole antenna having at least two tabs, and wherein the first and second loop antennas comprise tuned coils in which the tabs of the dipole antenna are placed across the coils to capacitively couple the tabs to the coils at the first and second frequencies.
5. The wireless communication device of claim 4 , wherein the tabs are asymmetrically shaped to form an asymmetrical dipole antenna.
6. The wireless communication device of claim 4 , wherein the first loop antenna and the second loop antenna form a pair of asymmetrical loop antennas in which the first loop antenna is smaller than the second loop antenna according to the position where the tabs of the dipole antenna are placed across the coils.
7. The wireless communication device of claim 1 , wherein a slotted ground plane is positioned between the pole antenna and the first and second loop antennas.
8. The wireless communication device of claim 1 , wherein at least one of the first loop antenna and the second loop antenna is formed of a first loop part and a second loop part that are both capacitively coupled to the pole antenna, and wherein the second loop part is nested within the first loop part.
9. The wireless communication device of claim 1 , wherein the first loop antenna is formed to be electrically longer than the second loop antenna, and wherein the first frequency of the first resonant circuit is lower than the second frequency of the second resonant circuit.
10. The wireless communication device of claim 1 , wherein a slotted ground plane is positioned between the pole antenna and the first and second loop antennas, and wherein the slotted ground plane comprises two plates positioned with a gap therebetween.
11. The wireless communication device of claim 10 , wherein the first frequency of the first resonant circuit is UHF, the second frequency of the second resonant circuit is a low frequency, and the third frequency of the third resonant circuit is a microwave frequency.
12. The wireless communication device of claim 11 , wherein the gap in the slotted ground plane has a low impedance at the third frequency.
13. A method of providing a wireless communication device, the method comprising: providing a pole antenna having at least one tab; connecting communication electronics to the pole antenna; positioning a first loop antenna proximate to the pole antenna to capacitively couple the first loop antenna to the pole antenna at a first frequency such that the capacitive coupling forms a first resonant circuit between the communication electronics and the first loop antenna at the first frequency; and positioning a second loop antenna proximate to the pole antenna to capacitively couple the second loop antenna to the pole antenna at a second frequency such that the capacitive coupling forms a second resonant circuit between the communication electronics and the second loop antenna at the second frequency; wherein the communication electronics and the pole antenna form a third resonant circuit configured to operate at a third frequency that is different from the first and second frequencies.
14. The method of claim 13 , further comprising positioning the pole antenna between the first loop antenna and the second loop antenna, wherein the first and second frequencies of the first and second resonant circuits are tuned according to the relative placement of the pole antenna between the first and second loop antennas.
15. The method of claim 13 , wherein the first loop antenna and the second loop antenna are formed of a microstrip.
16. The method of claim 13 , wherein the pole antenna is a dipole antenna having at least two tabs, and wherein the first and second loop antennas comprise tuned coils in which the tabs of the dipole antenna are placed across the coils to capacitively couple the tabs to the coils at the first and second frequencies.
17. The method of claim 16 , wherein the tabs are asymmetrically-shaped to form an asymmetrical dipole antenna.
18. The method of claim 16 , wherein the first loop antenna and the second loop antenna form a pair of asymmetrical loop antennas in which the first loop antenna is smaller than the second loop antenna according to the position where the tabs of the dipole antenna are placed across the coils.
19. The method of claim 13 , further comprising positioning a slotted ground plane between the pole antenna and the first and second loop antennas.
20. The method of claim 13 , wherein at least one of the first loop antenna and the second loop antenna is formed of a first loop part and a second loop part that are both capacitively coupled to the pole antenna, and wherein the second loop part is nested within the first loop part.
21. The method of claim 13 , wherein the first loop antenna is formed to be electrically longer than the second loop antenna, and wherein the first frequency of the first resonant circuit is lower than the second frequency of the second resonant circuit.
22. The method of claim 13 , further comprising positioning a slotted ground plane between the pole antenna and the first and second loop antennas, wherein the slotted ground plane comprises two plates positioned with a gap therebetween.
23. The method of claim 22 , wherein the first frequency of the first resonant circuit is UHF, the second frequency of the second resonant circuit is a low frequency, and the third frequency of the third resonant circuit is a microwave frequency.
24. The method of claim 23 , wherein the gap in the slotted ground plane has a low impedance at the third frequency.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 25, 2009
March 1, 2011
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